The invention relates to a receiver for a digital transmission system comprising an incoming arrangement for receiving a receive signal and including a signal processing means for recovering a transmitted data sequence from the received signal.
Receivers of this type are used, for example, in the future Pan-European mobile radio system GSM (Groupe Special Mobile), which is referenced D-network in Germany. In this mobile radio system, for example, speech signals are transmitted in digitized form together with other digital signals according to a Time-Division Multiple Access method (TDMA). The data are transmitted by a transmitter of the mobile radio system by means of a suitable modulation. Reflections and multipath propagation on the transmission path cause the transmitted signal to reach the receiver in various superposed signal portions with different delays and phase shifts so that the incoming signal is distorted. These distortions cause the binary digits contained in the received signal to be affected by preceding binary digits (intersymbol interference). A signal processing means comprising an equalizer eliminating these distortions is necessary for equalizing the originally transmitted data symbols.
JP 2-199936 (A) discloses a digital transceiver in which, for improving the transmission efficiency, the receiver comprises a device for determining the transmission quality that is, the amount of noise and distortion, as contrasted with the magnitude of the incoming signal. When there is a good transmission quality, this device applies a switching signal to an error correction means arranged at the transmitter and receiver ends, so that the error correction means is switched off.